Method of melting primary baths for dissolving ores.



UNITED STATES PATENT OFFICE.

ALLEN, OF LO LO, MONTANA;

BAGGALEY.

SAID ALLEN ASSIGNOR TO SAID METHOD OF MELTING. PRIMARY BATHS FOR DISSOLVING ORES...

Specification of Letters Patent.

:atenteci June 5, 1906.

Application filed December 19,1904. Serial No. 237,467.

To all whom, it may concern:

Be it known that we, RALPH BAGGALEY, of Pittsburg, Allegheny county, Pennsylvania, and CHARLES M. ALLEN, of Lo Lo, Missoula county, Montana, have invented a new and useful Method of Melting Primary Baths for Dissolving Ores, of which the following is a full, clear, and exact description.

Our invention, as more fully described hereinafter, is capable of being practiced in any convenient form of melting-furnace, cupola, or converter, and particularly such as are now used in smelting copper ores.

The object of our invention is especially to produce a primary bath, preferably from sulfid ores, for use in subsequently dissolving other ores rich in minerals and generally of a more silicious nature, as well as concentrates, carbonates, and oxids, and, indeed, all the various forms of ore in which copper, gold, silver, &c., are found in nature, as more fully described in a patent granted to us on Au gust 2, 1904, No. 766,654, for a method of recovering values from ores by dissolving in a molten bath.

The object of our present invention is also to produce such primary bath either with a very small proportion of carbonaceous fuel say, for instance, two per centum of coke or .even lessor when conditions are right after the ores have been once thoroughly ignited the .melting process may be carried on successfully entirely without the use of carbonaceous fuel. It is thus possible to melt pyrrhotite ores and some forms of sulfid ores entirely without the use of coke, providing such ore be charged into the furnace exclusively in large lumps that will provide air-passages for the blast, and provided, further, that a large volume of blast be used, and provided, further, that such ores contain suitable percentages of sulfur.

In present smelting practice from fifteen to twenty-five per centum of coke is found necessary, particularly where the ores under treatment are of a silicious nature. As coke is usually very expensive at points where copper ores are produced, the expenses for fuel constitute an important proportion of the total cost of treating ores. In present practice this heavy consumption of coke is due to the constant eflort to calcine the ores in the blast-furnace itself before the actual zone of fusion has been reached in order that and thereafter resmelting it.

such ores after fusion will produce a fifty-percent. matte for subsequent treatment in the converter. In all prior practice the aim has.

been to concentrate matte as quickly as possible and at every stage of the process. Sometimes this has been accomplished by calcining the ore, either in roast heaps or by stallroasting. An effort has also been made to calcine, and thus to concentrate, the ore in the blast-furnace through the medium of an oxidizing-blast. The same result is sometimes produced by scorifying the charge, as is done in reverberatory-furnace practice. It has also been produced by calcining the matte One of the strongest advantages claimed for pyritic smelting is that a great degree of concentration is possible in the matte through the use of a hot blast. In short, all methods of reduction that are now in use for treating sulfid ores aim at high concentration, whether the same be accomplished by water, by calcination, by smelting, or by converting. In all prior methods every unit of sulfur thus eliminated is lost for fuel purposes in subsequent treatment. This loss of sulfur has been peculiarly aggravated in prior methods of smelting, for the reason that calcination as a means of enrichment is always desired. If instead of present practice a simple melting operation is resorted to, much greater fuel values can be retained in the matte. These fuel values are of the greatest importance where the intention as, for instance, in the process described in the application above referred tois to subsequently smelt other ores, and particularly silicious mineral-bearing ores, through the oxidation of the sulfur, iron, and other elements and compounds contained in this matte. For the purpose stated. a simple melting of the ore is ideal practice.

In our present invention our aim is in the first melting operation to separate the mattemaking materials of the ore from those that are silicious and aluminous and to accomplish this separation with as little loss of sulfur as possible. The inevitable result of this practice is the production of a very low grade matte-that is to say, a matte that is low in mineral values and high in fuel values. In the subsequent process we thereafter reduce ores thatare higher in silica or in copper, gold, silver, &c.

In our invention the iron, sulfur, &c., contained in the ore and the oxygen contained in the air when properly combined constitute the sole fuel on which we depend in order to produce effective results. Therefore the less matte concentration thatwe effect in our first fusion of the ore the more fuel we will have with which to conduct our subsequent operations. Our present method is diametrically opposite to all prior smelting methods, in all of which an especial effort is made at all points to concentrate and to increase the grade of the matte, and such concentration must have the effect of sacrificing the fuel values contained in the matte for the reasons stated.

In prior practice a great effort is made to keep the matte up to grade, as it is called, which means up to fifty per cent. Cu, and the farther it falls below thefifty-per-cent. mark the stronger will be the effort to raise it. Where the ore primarily is of such low grade that very low-grade mattes must result from its fusion, it follows that not enough copper will be present in the matte to enable the operator to complete the blow. If an additional charge cannot be secured from the smelting-furnace, which is often the case in ordinary smelter plants, it then becomes necessary to blow up to a certain point in the converter and thereafter to transfer a supplementary charge from another converter, so as to provide a large enough body of con verter-matte to bring the two charges when combined in a single converter up to blistercopper.

In our present invention we aim to keep the grade of the matte primarily as low as possible consistent with the mineral values contained in the ores under treatment. Instead of attempting to increase the grade of our matte by calcination or otherwise in our first smelting operation, as is universally done in present practice, our constant aim is to lower its grade, for two reasons: First, by this practice we save sulfur and iron for use in the treatment of other more silicious ores on which we depend mainly for the copper, gold, and silver that we seek; second, as a means of adding to our productive capacity, and consequently the cheapening of the process in the first smelting operation. It is a well-known fact that an increase in the grade of the matte in a measure retards the free running of the furnace, everything else being equal.

In the light of the foregoing explanation it will be seen that our methods of procedure are the reverse of all prior practice. It is especially adapted to utilize the natural fuel contained in the ore and to utilize it to the best advantage. The waste of these substances that prevails in all present practice is eliminated by our invention, and by this invention we practically eliminate the use of carbonaceous fuels of all kinds, and thus avoid this heavy expense.

In the practice of our invention we take copper or iron sulfid ore containing, preferably, sixty-five per cent. or more of metal sulfids and charge it, preferably in large lumps, into a blast-furnace wherein we melt it either with the use of no carbonaceous fuel or with as little carbonaceous fuel as possible, a large volume of air being used. Care is taken to produce a matte which is only enriched to a slight degree by such operation. Thus the mere melting of the matte will usually add about four per cent. to its metal values, and sulfid ore which assaystwo per cent. of metal values will after melting produce a matte assaying about six per cent, and we prefer to adhere as close to such enrichment as possible. The matte which we thus obtain, containing, say, three to fifteen per cent. of metal values, is used as a primary bath for dissolving ores in the manner described and claimed in our patent above mentioned. We find that it is desirable in melting the ore to charge it into the furnace in large lumps.

We claim 1. The method of providing a primary bath for. dissolving ores which consists in passing through an ore of high fuel value a large volume of blast, and melting the ore with only such concentration as results from a simple melting; substantially as described.

2. The method of providing a primary bath for dissolving ores which consists in passing through an ore of high fuel value in large lumps a large volume of blast, and melting the ore with only such concentration as results from a simple melting; substantially as described.

3. The method of providing a primary bath for dissolving ores which consists .in passing through an ore of high fuel value a large volume of blast, and melting the ore and producing a matte which approximates as closely as possible to the original combinations of sulfur, iron, copper, silver, gold and the like in the ori inal ore as is consistent with the removal of the gangue from the ore; substantially as described.

4:. The method of dissolving ores, which consists in melting ore, separating the gangue therefrom without materially removing the sulfur, iron, copper, silver, gold and the like contained in the ore, whereby a primary bath is produced, and then dissolving ore in the primary bath, substantially as described.

In testimony whereof we have hereunto set our hands.

RALPH BAGGALEY. CHARLES M. ALLEN.

Witnesses:

A. E. HOBART, WILLIAM M. KIRKPATRICK.

ITO 

